<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<script>
    let node  =window.document.documentElement
    console.log(window.document,window.document.nodeType,node,node.childNodes)
    document.writeln(`123456`)
</script>
</body>
</html>
